1. Field of the Invention
The embodiments of the present invention relate to a mechanical pencil and more specifically to a mechanical pencil comprising a tubular body extending along a longitudinal axis between a rear-end which has a first opening and a front-end which has a second opening through which a lead can move out and a mechanism for advancing the lead arranged within the tubular body, where the advancing mechanism comprises:                a pushing device suited for sliding parallel to the longitudinal axis and including an external portion which extends outward relative to the tubular body and an inner portion inserted into the tubular body through the first opening.        a chuck located at the front end side of the tubular body and which could be tightened onto the lead;        a reservoir which extends along the longitudinal axis for housing at least one lead, where the reservoir comprises a rear end surrounded by the internal portion of the pushing device and a front end suited for moving the chuck when the pushing device slides towards the front end.        
2. Description of Related Art
A mechanical pencil of the aforementioned kind compensates for the wear at the front end of the lead by sliding it relative to the tubular body in response to an axial pressure on the pushing device where the tightening chuck then locks the new position taken by the lead in a well-known manner. During an operation for reloading a lead into the reservoir, the user must simply slide the lead through a central opening, generally narrower than the reservoir, conventionally formed in the pushing device. A removable eraser is generally mounted on the pushing device and covers this central opening in the mechanical pencil's operating configuration.
As an example, the document U.S. Pat. No. 5,354,141 or its equivalent WO 92/15462
A1 disclose a mechanical pencil which includes a pushing device formed from the eraser support and the eraser cap, with a possible eraser-cover, and slidably mounted in a cylindrical barrel. The actuation of the advancing mechanism and the erasing can be done easily with this type of pushing device.
The inside portion of the pushing device can engage with a reservoir whose diameter is reduced compared to the inside diameter of the tubular body. The thrust serves to stop axially on an annular rim at the rear end of the reservoir in order to drive the reservoir forward. The fact of having a reservoir that is significantly narrower than the tubular body is advantageous for getting an easier and faster centering of a new lead in the gripping area of the advancing mechanism.
In the mechanical pencil described in this document, the inner portion of the pushing device includes an elastically deformable thinning portion provided with one or several projecting tabs which engage with an inner shoulder or a window of the barrel in order to form a stop retaining the pushing device. However, a drawback related to the flexibility of the inner portion of the pushing device is that it is easier to break the deformable part of this inner portion, for example during assembly or when a significant force is exerted on the pushing device (for example during energetic erasing). There is then a risk of the pushing device becoming detached from the barrel and lost.